Kinetics and mechanism of oxidation of γ-oxoacids by acid permanganate

Abstract

Kinetics of oxidation of unsubstituted and substituted <em>γ</em>-oxoacids by acid permanganate in aqueous acetic acid medium have been studied at high and low [H₃O⁺]. At high [H₃O⁺], the reaction is first order each in [oxoacid], [MnO] and [H₃O⁺]. At low [H₃O⁺], the reaction is zero order in [MnO] and first order each in [H₃O⁺] and the [oxoacid].Variation in ionic strength of the reaction medium has no significant effect on the rate of oxidation. But the rate of the reaction is enhanced by lowering the dielectric</p> constant of the reaction medium. Electron-releasing substituents in the aromatic ring accelerate the reaction rates and electron-withdrawing substituents retard them. The value of the reaction constant (<em>ρ</em>) at 303 K (at [H₃O⁺] = 1<em>M</em>) obtained from the Hammett's plot is -1.49 (corr. coeff. = 0.998). A mechanism consistent with the observed results has been suggested and the related rate laws deduced. Activation parameters have been computed.